The long-awaited letter from Virginia Tech arrived at Courtney Zahra's house in Great Falls in late May.

The good news was that after being stuck for several weeks on the waiting list, the senior at Fairfax County's Langley High School had gotten in. The bad news was that she could not attend Virginia Tech until January and that she would have to take classes at another college first. There was no room for her at Virginia Tech in the fall, school officials explained, but slots would become open in the spring term because of students leaving.

Zahra had been accepted at four other colleges, but Virginia Tech had a gorgeous campus and an education training program she liked. So she accepted its invitation to enroll late. "It's one of those gut feelings," she said. "I just knew that was where I wanted to go."

All over the country this summer, incoming college freshmen are wrestling with unconventional offers like the one made to Zahra, in the aftermath of what many educators say was the most competitive college admissions season ever.

A combination of rising high school enrollment and teenagers' increased interest in college led to a crush of applications, and more students than ever were stranded on waiting lists this spring, university officials say. That has prompted many colleges to find creative ways to squeeze in more freshmen, which makes applicants happy and increases school revenue.

Many schools, like Virginia Tech, have offered students admission next spring. Others accepted students for the term that began this summer, seeing it as a way to enlarge their freshman class while mitigating crowding problems in the fall. Still other colleges are trying to make more room by inviting older students to move off campus, cutting back on transfer students or using product management techniques first developed in factories and supermarkets.

Trent Anderson, executive director of pre-college and pre-graduate programs for Kaplan Educational Centers, a test preparation company that is owned by The Washington Post, estimates that at least half of the more than 4,000 four-year colleges in the country have adopted admissions systems that diverge from the normal fall enrollment.

Zahra was among 200 students who accepted admission at Virginia Tech for January. For the fall semester, 4,700 student accepted admission. Shelley Blumenthal, associate director of undergraduate admissions at the Blacksburg, Va., school, said its spring admissions policy began two years ago as the college's popularity reached new heights.

Many strong students were applying "to whom we would have offered [fall] admission before, but because of the competition and the increasing strength of the applicants, we had to place these students on the waiting list," he said.

Anderson and other specialists predict that the trend of so-called multi-entry dates for college students will only become stronger in the coming years. A record 14.8 million students are registered to attend four-year institutions this fall, and that number will keep increasing as the children of baby boomers push high school enrollment to an expected peak a decade from now.

Also fueling the trend are modern computer systems that allow universities to keep better track of semester-by-semester fluctuations in enrollment and dormitory space.

In recent years, Colby College, in Waterville, Maine, has offered more than 100 students each year a chance to start school in January after spending the fall term at Colby-sponsored study centers in France, Spain or England. This spring, 70 students, twice the usual number, signed up, forcing the school to find more European housing.

But Colby still has too many students coming this fall, said Steve Thomas, director of admissions. Because of the competition for college space, about 500 students accepted fall admission to Colby instead of the usual 475. The school is making room in its dormitories by giving more seniors permission to live off campus, but some classrooms will be more crowded.

Harvard University decided four years ago to cut the number of transfers it admitted from about 110 to 75 so it could accept more high school seniors. "We were turning away magnificent applicants whom we did not want to turn away," said Marlyn McGrath Lewis, Harvard director of admissions.

The University of Maryland has offered spring admission to about 600 wait-listed students in each of the last three years, and about 250 each year have accepted, said U-Md. spokesman George Cathcart. Unlike Virginia Tech, Maryland does not require that those students attend another college in the fall.

Jack Blackburn, dean of admission at the University of Virginia, said his school does not admit students in the spring and would have few places for them if it did. "The student who pulls out at midyear is so rare," he said.

One of the most sophisticated approaches to rescuing the wait-listed takes place at the University of Florida at Gainesville. The school accepts new students in the fall, spring and summer quarters, and many of those who start in the summer take breaks at other times of the year, thus easing the strain on facilities. School officials also keep a computerized inventory of which courses each student needs to graduate and when the student should take those classes. Some pre-med students who need organic chemistry will be told to take it in the fall, for example, while others will take it in the summer.

The new system has allowed the university to admit more students and still avoid crowding in key courses, school officials say. University of Florida President John V. Lombardi likens it to the method factories and stores use to ensure that products arrive just when customers need them.

Most colleges that admit in the spring or summer do not include those students' Scholastic Assessment Test scores -- which typically are lower than the SAT scores of fall admittees -- when calculating the average SAT score of the freshman class. That ensures that the college will not suffer a lower ranking in lists such as the one published by U.S. News and World Report magazine, said Sheldon E. Steinbach, general counsel for the Washington-based American Council on Education, who called the practice "one of our dirty little secrets."

But officials at schools that are dipping deeper into their waiting lists say they are admitting students with first-rate credentials and are not lowering their standards in any way.

Zahra, for example, was a yearbook editor and a strong B-plus student at Langley, one of the most academically challenging high schools in the state. Teachers raved about her leadership qualities and her work with hearing-impaired and developmentally disabled children, but her SAT scores were below those of other students with similarly attractive applications.

Zahra's counselor, Brian Doyle, and Langley's college and career counselor, Brenda Whalen, called and e-mailed Virginia Tech admissions officers on her behalf. Karen Torgenson, the college's director of undergraduate admissions, called Doyle back to tell him that she thought Zahra would be a good candidate for the expanded spring admission program.

A May 27 letter told Zahra she had to enroll for the fall in an acceptable community college or four-year school and compile a grade point average of at least 2.5 with no grade less than a C. In this way, Virginia Tech officials said, their spring admittees can still count on graduating in four years.

Zahra said she plans to enroll at Northern Virginia Community College and keep her job at a nearby telemarketing firm until she moves to Blacksburg.

High school counselors have begun to embrace the new admissions systems. Bob Turba, chairman of guidance services at Stanton College Preparatory School, a public school in Jacksonville, Fla., said many of his students, often from families with few college graduates, like the summer term option offered at many Florida state schools.

"It is easier for them to get in, and if they take a course or two in the summer and are successful, they just move on into the fall semester," he said.

Olivia Odell, 18, who is in her first month of college at the University of Florida, said she sees many advantages to summer admission. "There are less people, and the classes are smaller," said Odell, who is pursuing a degree in health science education. "Summer is a terrific time to come to college and just learn where everything is."

At the University of California system headquarters in Oakland, officials are discussing a major expansion of summer classes to help absorb an anticipated 40 percent jump in applicants over the next 12 years. "Whenever you begin to worry about capacity, you think about doing something in the summer," said Sandra Smith, assistant vice president for planning and analysis.

Paul Marthers, senior associate director of admissions at Oberlin College in Oberlin, Ohio, said the strength of wait-listed applicants persuaded his school to approve a few spring admissions this year, but he recommended that it do this very carefully.

"Jumping in midyear is like entering a party in progress," he said. "Students need to feel connected to the school and not like second-class citizens who snuck in through the back door."